Education expert Keir Bloomer, one of the architects of the curriculum, also raised concerns over Education Scotland's performance.

Mr Bloomer, convener of the Royal Society of Edinburgh's education committee, backed a review of the body on BBC Radio Scotland's Call Kaye programme.

He said: "Education Scotland is Scotland's fourth attempt to set up a curriculum agency.

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Ms Sturgeon has pledged to cut the attainment gap between rich and poor pupils

"None of them have really had the confidence of teachers, and at the back of that is a dilemma about what the curriculum agency is for.

"Teachers believe it's there to help them. Government believes it's there to ensure government policies are carried out. Those two are very different things."

But Education Secretary John Swinney earlier rejected concerns about a conflict of interest.

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Education Scotland said it was 'confident' of increasing inspections

"Because what Education Scotland is focussed on, whether it's in its role as inspectors of schools or in developing the curriculum, is that both of these functions are focussed on improvement, on making sure education is being strengthened," he told Good Morning Scotland.

Education Scotland said it was "confident" of increasing inspections.

A spokeswoman said: "The reality is we will see no fall in the number of inspections this year and we will see a significant increase in 2017/18.

"The projections provided to the Education Committee were correct at the time they were collated, however the exact number of inspections regularly change in-year as resources are redeployed."